As is known to those who are skilled in the art, a portable pipe bending machine is made up of two fundamental parts. The first one is a piston actuating member operated with hydraulic, pneumatic or mechanical manual control means, if desired assisted by an electric motor. Specifically, a piston is provided, mounted within an oleodynamic cylinder with a handle control. The second part is the working member, that is to say the bending or curving head. It comprises a matrix with a groove that receives the pipe to be bent, which matrix is made to advance linearly or it is made to rotate with the pipe in its groove, bending the pipe itself against the rest of two shoulders. The actuation of the matrix is carried out by exploiting the displacements of the aforementioned piston, transforming them into angular advances with suitable mechanisms in the case of a rotating matrix.
In the earliest pipe bending apparatuses the two aforementioned parts, that for controlling and that for bending, were connected in a fixed manner. This, however, was uncomfortable for the operator, in that the controlling handle was not always in a position of easy manoeuvrability, once the bending head was positioned for the operation.
Then, this drawback was obviated by providing a coupling that was turnable perpendicularly to the axis of the actuating piston, in order to be able to have the handle always in the position of best manoeuvrability for the operator.
The turnable couplings known heretofore are ball couplings. They allow a relative rotation of the hydraulic cylinder, with which the handle is integral, and of the bending head, connected to the cylinder with a mouthpiece neck interfaced through a ball device.
However, ball couplings suffer from the drawback of being not fixable once the optimum angular position of the handle has been found, though affording a certain stability. That is to say, the handle during the bending operation, is subjected to displacements from the optimum position.
The object of the present invention is to obviate such a drawback.